402 



FAMILY XI. STAPHYLTNIDJE. 



KEY TO INDIANA GEO'UPS OF STENUS. 



a. Abdomen strongly and distinctly margined along the sides. 



ft. Fourth joint of tarsi simple. Group I. 



l)~b. Fourth joint of tarsi bilobed. Group II. 

 aa. Abdomen not distinctly margined, faint traces of a marginal line being 

 visible only on first segment. 



c. Fourth joint of tarsi simple or but slightly enlarged. Group III. 



cc. Fourth joint of tarsi distinctly bilobed. Group IT . 



Group I. 



This group, on account of its size, Casey also separated into the 

 following divisions : 



KEY TO DIVISIONS OF GROUP I. 



a. Elytra each with an orange spot near the middle of the disk. 



Division A. 



aa. Elytra without pale spot. 



1). Punctures in some portion of the elytra more or less joined or coales- 

 cent sometimes only in twos or threes, sometimes in long channels. 

 c. The channels or rows of punctures in some one spot on the surface 

 of each elytron arranged in a spiral or whorl which is complete 

 or very nearly closed. Division B. 



cc. The channels or rows of united punctures often sinuous but never 

 forming a completed vortex or whorl. 

 d. Thorax with a more or less distinct median chanuel or groove. 



Division C. 



dd. Thorax without trace of median groove. Division D. 



1)1). Punctures of elytra all isolated and distinct one from another. 



Division E. 



Division A. 



The species of this division are among the largest in the genus. 

 They are easily recognized by the orange colored spot on each ely- 

 tron. Two species have been taken in Indiana, while another 

 doubtless occurs. 



KEY TO SPECIES OF DIVISION A. 



a. Femora black: length 4.5-5 mm. 778. bipunctatus. 



aa. Femora not black, ranging in color from dark piceous-brown to dull yel- 

 low. 



1). Head wider than elytra, spot on latter bilobed ; length 3.6-4 mm. 



779. colon. 



bb. Head equal in width to elytra, spot rounded: ninth and tenth joints 

 of antenna? equal ; length 3.8^.4 mm. semicolon. 



778 (2303). Stenus bipunctati 1 s Erichs., Col. March.. 1837. 530. 



Rather robust. Black, feebly bronzed, shining, very finely and sparsely 

 pubescent ; elytra each with a small, pale, rounded spot just behind the 

 middle. Head less than twice as wide as long, deeply excavated and finely 

 punctured between the eyes ; antennae reaching middle of thorax, the third 



